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3.3 Type-Casting

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Ch. 3 Data

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What is Type Casting?

Type casting is where you can convert a variable’s numeric data type into another one. This is really handy if you want a variable to be more precise/less precise. There are two types of type casting in Java: widening casting and narrowing casting.
 

Widening Casting

Widening casting is where you want to convert from a smaller numeric data type to a larger data type. Fortunately, this is automatically done by Java, so you don’t have to do anything here. But, it is still important to understand the logic.
byte → short → char → int → long → float → double
 
Here’s an example:
public class MyClass { public static void main(String[] args) { int myInt = 9; double myDouble = myInt; //Automatic casting: int to double System.out.println(myInt); //Outputs 9 System.out.printlin(myDouble); //Outputs 9.0 } }
 

Narrowing Casting

Narrowing Casting is pretty much the opposite of widening casting in that you use it when you want to convert a larger data type into a smaller one. This is not automatically done by Java, so you have to manually do it.
double → float → long → int → char → short → byte
 
To narrow cast, you put the data type that you want to cast the variable into in a pair of parentheses. For example, if I have a variable of type double and I want to convert it into an int, then I would put int in front of the variable. Here’s an example:
public class MyClass { public static void main(String[] args) { double myDouble = 9.78; int myInt = (int )myDouble; //Manual casting: int to double System.out.println(myDouble); //Outputs 9.78 System.out.printlin(myInt); //Outputs 9 } }
 
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